#include<stdio.h>
int main()
{
	    int n,i=1,result=1;
	    printf("please enter a enter:\n");
	    scanf("%d",&n);
	for(i=1;i<=n;i++){
		result*=i; 
	}
	printf("%d!=%d\n",n,result);
	return 0;
 } 
